Method for dyeing cellulose triacetate using anionic dyes

ABSTRACT

A PROCESS FOR DYEING TEXTILE MATERIALS OF CELLULOSE TRIACETATE WHICH COMPRISES CARRYING OUT THE DYEING AT A TEMPERATURE BETWEEN 105* AND 140*C. UNDER PRESSURE IN AN AQUEOUS DYEING BATH CONTAINING AT LEAST ONE WATERSOLUBLE ANIONIC DYE, GLYCERIN TRIACETATE AND BETWEEN 10 AND 120 G./I. OF A SALIFYING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND SODIUM SULPHATE.

United States Patent 3,623,833 METHOD FOR DYEING CELLULOSE TRIACETATE USING ANIONIC DYES Amerigo Wildermuth, Milan, and Ferdinando Marchi, Cesano Maderno, Italy, assignors to Aziende Colori Nazionali ACNA S.p.A., Milan, Italy No Drawing. Filed Mar. 7, 1969, Ser. No. 805,366 Claims priority, application Italy, Mar. 11, 1968, 13,808/68 Int. Cl. D06p 1/20, 3/40 US. C]. 84() Claims ABSTRACT OF THE DISCLOSURE A process for dyeing textile materials of cellulose triacetate which comprises carrying out the dyeing at a temperature between 105 and 140 C. under pressure in an aqueous dyeing bath containing at least one watersoluble anionic dye, glycerin triacetate and between 10 and 120 g./ l. of a salifying agent selected from the group consisting of sodium chloride and sodium sulphate.

The present invention refers to a process for dyeing cellulose triacetate fibers by an aqueous dyeing bath containing anionic dyes.

Cellulose triacetate, in which practically all of the reactive OH groups of the cellulose molecule are acetylated, possesses technical characteristics which are definitely superior to those of normal diacetate in which about only 80% of the hydroxyls are esterified.

Cellulose triacetate fibers, compared to those of diacetate, possess the following advantages:

considerably higher resistance to heat;

considerably higher resistance to alkalis; possibility to obtain permanent pleatings; lesser water absorption and faster drying.

Nevertheless, from the dyeing point of view, the cellulose triacetate has several drawbacks. Since all three of the hydroxyl groups of the cellulose molecule are esterified, only a very small number of reactive groups remain for forming hydrogen bonds with the dyes. Furthermore, the fiber is very crystalline and hydrophobic and the dispersed dyes apt to dye it have a very low speed of diffusion in the fiber. The dyeing with dispersed dyes (plastosoluble dyes), even when suitably selected, does not always solve certain problems of brightness and fastness (stability) to heat treatments.

Therefore, dyeing with anionic dyes, which combine brightness, good fastness to wet treatments, and an excellent fastness to sublimations, presents a stronger interest for the dyers.

It is known that certain anionic dyes may be adsorbed by triacetate rayon by means of the foulard process or by the printing process, giving dyes and prints characterized by a good fixability and by a good general fastness. British Pat. No. 1,029,743 describes a dyeing process by foulard impregnation or by printing of synthetic textile materials and in particular fabrics made from cellulose triacetate, by means of foularding baths, or by printing pastes containing at least one water-soluble acid dye for W001, a mixture of particular auxiliary dyeing substances like resorcin, benzoic acid, thiourea, together with a thickener and, as necessary, with other conventional additives known in the prior art of dyeing. Subsequently, the material thus impregnated is subjected to heating and steam treatment.

These formulations turn out to be well suited for being applied to foularding and in printing, but give negative results in the full-bath dyeing or exhaustion dyeing, inasmuch as it has been found experimentally that under such conditions the triacetate does not dye in the least. The full-bath dyeing, involving the exhaustion of the bath, is of primary importance since it is applied in the dyeing of yarns (hanks, reels, cakes) and for small and medium processing capacities.

An object of this invention is to eliminate the aforementioned drawbacks and of providing a method which will allow a better dyeing of cellulose triacetate in fullbath.

We have surprisingly found that intense dyeings are obtained, characterized by excellent fastness to thermal treatments and in particular to sublimation, when the dyeing of the cellulose triacetate textile material is carried out in an aqueous dyeing bath containing at least one water-soluble anionic dye, glycerin triacetate and quantities of a salifying agent, such as for instance sodium chloride, sodium sulphate, etc., at between 10 and g./l., by operating under pressure and at temperatures comprised "between 105 and C.

According to a convenient form of embodiment of this invention, the swelling and softening action of glycerin triacetate (technical triacetin of standard issue in the dyeing plants) is very specific and rather high, so that just a few grams per liter (from 1 to 7 g./l., but preferably from 3 to 5 g./l.) are quite sutficient for obtaining best results.

Further additions of triacetin within the limits of its solubility in water, although they are only contraindicated because of cost, would not improve the quality of the dyeings obtainable.

Anionic dyes particularly suited for carrying out the dyeing process of this invention, are the acid dyes with a low degree of water solubility and a reduced or medium molecular weight, such as for instance the monoazomonosulphonic dyes and the antraquinone-monosulphonic dyes, the pre-metallized 1:2 dyes, primarily intended for the dyeing of natural and synthetic polyamide fibers, preferably in a neutral dyeing bath.

Thus, just for exemplifying purposes, the following dyes are conveniently applicable with this process:

Giallo Novamina Solido C2G (C.I. Acid Yellow 61) Giallo Novamina 2GP (C.I. Acid Yellow 39) Roccellina CS (C.I. Acid Red 141) (C.I. 15625) Rosso Novamina B (C.I. Acid Red 62) Violetto acido Brillante 6BN (C.I. Acid Violet 15) (C.I.

Blu Cielo Alizarina R (C.I. Acid Blue 62) (C.I. 146-46) Blu Alizarina A (C.I. Acid Blue 41) (C.I. 62l30) Giallo Stenolana GL (C.I. Acid Yellow 140) Arancio Stenolana RLN (C.I. Acid Orange 104) Grigio Stenolana BLN (C.I. Acid Black 133) Giallo Novamina Solido CZG (Acid Yellow 61) is an equimolar mixture of the two dyes and w I N SO N(C H 1 S O Na This dye is prepared by dissolving at 70 C. 0.04 mole of 1-amino-4-methyl-3-N-ethyl-N phenyl sulfonamide and 0.06 mole of 1-amino-2-methyl-S-N-ethyl-N-phenylsulfonamide in 250 g. water and 50* g. of HCl 30%, and pouring the solution in a mixture comprising 100 g. water, 300 g. ice and 7 g. of a 20% aqueous solution of NaNO (sodium nitrite).

The reacting mixture is clarified with diatomite, and then it is poured in a mixture consisting of water (150 g.), ice (150 g.), NaOI-I (17.5 g.), sodium acetate (25 g.) and 1 (2',5 dichloro-4'-sulfo-phenyl)-3 methyl-5-pyrazolone (35 g.). The resulting mixture is reacted to complete copulation and then the dye is separated therefrom by salting with NaCl and filtering.

Giallo Novamina 2GP (Acid Yellow 39) is prepared according to the process described in connection with the dye Giallo Novamina Solido C2G, but starting from 0.1 mole of 1-amino-2-methyl-S-N-phenyl-sulfonamide, in lieu of the two sulfonamides used to prepare the former dye.

Rosso Novamina B (Acid Red 62) is prepared by pouring 12.5 g. of a 20% aqueous solution of NaNO (sodium nitrite) into a solution comprising water (290 g.), HCl 30% (63 g.), ice (400 g.) and 1-amino-2-methoxy-5-N,N-diethyl-sulfonamide (47.5 g.). The diazo compound thus formed is gradually poured into a solution comprising water (360 g.), ice (150 g.), sodium carbonate (900 g.) and 1-naphtol-4-sulfonic acid (42.5 g.).

The mixture is reacted by stirring at room temperature during 12-15 hours. Thereafter the dye is filtered and dried at 90 C.

Giallo Stenolana GL (Acid Yellow 140) is a metallized dye prepared according to the process disclosed in Example 7 of British patent specification No. 988,829.

Arancio Stenolana RLN (Acid Orange 104) is a metallized dye prepared according to the process disclosed in Example 3, lines 66-86 of British patent specification No. 988,829, but using in lieu of 42.1 g. of. the monoazoic compound described in said example (lines 677l), 46 g. of the monoazoic compound (M.W. 456.33) obtained by coupling, in alkaline medium, the diazo salt of the 4-N-methyl-sulfoamide-2-aminophenol with 1-(2',5' dichlorophenyl)-3-methyl-5-pyrazolone, all the other conditions being the same.

Grigio Stenolana BLN (Acid Black 133) is disclosed in Example 1 of British patent specification No. 998,870.

As salifying agents, sodium chloride can be used, but sodium sulphate is preferred, in quantities between 10 and 120 g./l. Concentrations, falling within the lower part of this range, of the salifying agent (10-30 g./l.) are required by the pre-metallized 1:2 dyes, while the concentrations in the upper zone (70-120 g./l.) are required by the classical acid dyes.

The operations for the execution of dyeing at 2%, according to the process of this invention, may be carried out, for instance, in the following way:

The anionic dye is dissolved in water at 50-60 C. and this solution is then poured into the dyeing apparatus. Thereupon there are added about 4 ml./l. of glycerin triacetate and about 100 g./l. of anhydrous sodium sulphate (for the pre-rnetallized 1:2 dyes, about 2025 g./l.). The dyeing apparatus is then closed and the dyeing is carried on for 1 hour at 128 130 C., with the bath under continuous circulation. Upon completion of the dyeing, the material is washed or rinsed and then treated with a bath containing about 2 g./l. of anionic detersive or scour of the type Diapon T (registered trademark).

The advantages attained through our process, in the dyeing of cellulose triacetate with anionic dyes, are:

(1) Improved fiastness of the dyeings, obtained above all under the thermal treatments of dry and wet fixing.

(2) The possibility of dyeing limited quantities of textile material, using under pressure standard equipment for the dyeing of Terital (R) (polyester fibers), equipment which is normally found in most dyeing plants.

(3) The anionic dyes are less expensive than the dispersed dyes normally used in this field.

The exhaustion of the dyeing bath in general is quite good. However, it is possible to improve the degree of exploitation of the dye by operating with a very narrow fiber/bath ratio, even of 1:1, thereby favoring the exhaustion of the dyeing bath. Or, once the dyeing method has been adjusted industrially, the same bath, suitably restored, may be exploited for successive dyeings.

The examples which follow hereunder, illustrate the aspects of the invention without thereby limiting the invention itself, all parts and percentages being by weight.

EXAMPLE 1 Into a plant suited for dyeing yarns in reels, cakes, tops on bobbins, packed staples, warp beams or cloth beams, operating on the cycling-bath system and at high temperature, were introduced and dissolved in 1000 parts of water at 60 C.:

Parts Rosso Novamina B (C.I. Acid Red 62) 4 Glycerin triacetate (triacetin) 4 Anhydrous sodium sulphate The material to be dyed consisted of 200 parts of a yarn of cellulose triacetate wound on a suitable perforated reel. The apparatus was then closed and dyeing was carried on for 1 hour at 128-130 C. in a cycling bath.

After the dyeing operation, the dyed material was treated in the same installation for 20 minutes at 40 C. with a solution consisting of 2 parts of sodium salt of the oleylmethyltauride dissolved in 1000 parts of water. The dyed material was then thoroughly rinsed in cold water and dried in a current of air at 60 C.

The triacetate yarn turned out to be dyed in a bright red with good intensity and showing an excellent general fastness.

EXAMPLE 2 Into the same under-pressure dyeing plant described in Example 1, wherein a perforated reel was substituted by a perforated beam having 200 parts of cellulose triacetate fabric wound thereon, were loaded:

Parts Water at 60 C. 1000 Blu Alizarina A (C.I. Acid Blue 41) 8 Triacetin 4 Anhydrous sodium sulphate 100 The dyeing apparatus was then closed and the dyeing was carried on for 1 hour at 128130 C., the dyeing bath being circulated by a pump. The dyed material was then treated, with the bath still circulating, at 40 C. for 20 minutes with a solution consisting of 2 parts of the product based on sodium salt of the oleylmethyltauride dissolved in 1000 parts of water. The material was then Washed with cold water and dried in an air current at 60 C.

The triacetate fabric appeared dyed with a good intensity in a bright blue shade and showing excellent characteristics of fastness to wet treatments.

EXAMPLE 3 Into an installation suited for dyeing yarns in reels with a circulating bath and having a heater for high temperatures, were loaded:

The apparatus was then closed and the dyeing was carried on for one hour at 128130 C., the bath being circulated by a pump. The material to be dyed was wound on a suitable perforated reel and consisted of 200 parts of cellulose triacetate yarn. After the dyeing operation, the material was treated in the same plant for 20 minutes at 40 C. with a solution consisting of 2 parts of sodium salt of the oleylmethyltauride, dissolved in 1000 parts of water. Thereupon the whole was rinsed with cold water and was then dried in a current of air at 60 C.

The triacetate yarn turned out to be dyed with a strong intensity in a brilliant (bright) blue tone, showing excellent general characteristics of fastness.

EXAMPLE 4 Into the apparatus described in Example 2 were loaded:

The material to be dyed consisted of 200 parts of cellulose triacetate fabric wound on a suitable beam. The apparatus was then closed and dyeing was carried on for one hour at from 128 to 130 C. in a bath kept circulating.

The dyeing bath was then discharged and the dyed material was treated in the same apparatus for 20 minutes at 40 C. with a solution consisting of 2 parts of the product based on sodium salt of the oleylmethyltauride dissolved in 1000 parts of water. The material was then thoroughly washed with cold water and then dried in an air current at 60 C.

Thereby was obtained a dyed material of a yellow tone with excellent fastness to wet treatments.

The pressure reached' in the apparatus was caused by the elevated temperature and is not critical, provided by operating temperature is used.

We claim:

1. A process for dyeing textile materials of cellulose triacetate, which comprises carrying out the dyeing at a temperature between and 140 C. under pressure in an aqueous dyeing bath containing at least one watersoluble anionic dye, glycerin triacetate and between 10 and g./l. of a salifying agent selected from the group consisting of sodium chloride and sodium sulphate.

2. The process of claim 1, wherein the aqueous dyeing bath contains, together with said glycerin triacetate, at least one water-soluble monoazo-monosulphonic dye of low to medium molecular weight and from 80 to 120 g./l. of salifying agent.

3. The process of claim 1, wherein the aqueous dyeing bath contains, together with said glycerin triacetate, at least one water-soluble antraquinone-molonsulphonic dye of low to medium molecular weight and from 80 to 120 g./l. of salifying agent.

4. The process of claim 1, wherein the aqueous dyeing bath contains, together with said glycerin triacetate, at least one Water-soluble pre-metallized 1:2 anionic dye, and from 10 to 30 g./l. of salifying agent.

5. The process of claim 1, wherein the aqueous dyeing bath contains between 2 and 7 g./l. of glycerin triacetate.

References Cited UNITED STATES PATENTS 2,188,160 1/1940 Rooney et a1. 8162 3,153,563 10/1964 Warner et al. 8-173 FOREIGN PATENTS 1,029,743 5/1966 Great Britain 8173 OTHER REFERENCES C. E. Mullin: Acetate Silk and Its Dyes, 1927, pp. 38, 139, 253 and 338339.

Exparte Schoeneberg et al., decision of the Board of Appeals, Pat. No. 3,190,718, Paper No. 27, 4 pages.

Exparte Schoonover et al., decision of the Board of Appeals, Pat. No. 2,743,991, Paper No. 23, 6 pages.

GEORGE F. LESMES, Primary Examiner T. I. HERBERT, JR., Assistant Examiner US. Cl. X.R. 8-50, 162 R, 173 

